Messages of this betrayal were sent north to Lindon where the High King Gil-galad ruled, and he began amassing his forces, preparing for an invasion. He also called for help to Númenor.

In 1695 S.A. Sauron attacked, and Elrond was sent to Eregion by Gil-galad. However, in 1697 S.A. Eregion was laid waste. Celebrimbor, lord of Eregion, was killed, and Khazad-dûm's gates were closed. Elrond fled north with the survivors, founding Imladris (later Rivendell).

By 1699 S.A. all of Eriador fell under Sauron's control, and he set fire to the great forests in Enedwaith and Minhiriath to drive off the Elves and their allies (Edain). Imladris was besieged, and Lindon cut off from Imladris and Khazad-dûm.

The next year a great army of Númenor arrived, sent by Tar-Minastir, which landed in Lindon, at Tharbad on the Gwathló, and south near Pelargir. Sauron's forces were caught in between the armies, and destroyed. The war ended in 1701 S.A. when Sauron retreated to the east, but Eregion was gone, and most of Eriador destroyed.